A capacitor is a passive two-terminal electrical device used to store energy within an electric field, and contains at least two electrodes separated by a dielectric layer. A capacitance of the capacitor is proportional to an area between the electrodes, and inversely proportional to a distance between them, (also a thickness of the dielectric layer). Accordingly, the capacitance can be increased by increasing the area between the electrodes, or decreasing the distance between them.
Capacitors not only store electric charge, but also block direct current (DC) while allowing alternating current (AC) to pass. Some examples of capacitors include deep trench (DT) capacitors and metal-insulator-metal (MIM) capacitors. DT capacitors are formed directly within a substrate, while MIM capacitors are formed on back end of line (BEOL) metallization layers.
In some circuit applications, decoupling capacitors (DECAPS) are utilized to decouple one part of an electrical network from another. In some RF and analog device applications, an array of MIM capacitors may be utilized. For instance, gain amplifiers, equalizers, filter circuits, and analog-to-digital converters include an array of programmable capacitors, which may be formed by MIM capacitors. In such applications, matching of device characteristics between the various MIM capacitors of the array is critical to device functionality.